Treatment of textiles to impart water-repellence



Patented June '2, 1942 TREATMENT OF TEXTILES TO IMPART WATER-REPEILENCE William E. Hanford and Donald 1*. Holmes, wn-

mln ton, Del., assignors .to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application October 8, 1937,

Serial No. 168,084

Claims.

This invention relates to cellulosic materials and particularly tothe treatment of these materials to render them, repellent to water.

Cellul'osic materials are not naturally waterrepellent. Methods of water-proofing fabrics by filling the interstices thereof by means of rubber, resins, etc. have long been practiced, with some degree of success. This is not, however, a sufflcient answer to the problem since for many uses it is highly, desirable that the fabric be water-repellent'but that the interstices be left substantially unchanged and that the fabric in general be left substantially unchanged in appearanceand feel. Methods have been devised for example heating with soap and alum, im-

pregnating with an emulsion or solution of waxy materials, etc., which attempt to attain this latter end but'these methods in general suffer from the defect that the water-repellency is not permanent and is more or less readily removed in a few launderings. (See Business Week, July 24, 1937, page 24). The finish produced by such treatments is not permanent and the fabric soon loses its water-repellency..

This invention has an object the improvement of cellulosic materials, fibers, or fabrics such as cotton, regenerated cellulose, artificial silk, paper, etc., by a treatment designed to markedly decrease their ability to wet with water without in any way injuring the structure, appearance or feel. A further object is the imparting to vegetable or artificial cellulosic fibers orfabrics made therefrom a high degree of water-repellency which isnot lost upon subjection to the usual laundering procedures. A further object is the preparation of spot-proof fabrics. A still further object is the preparation of improved a'wning materials, shower curtain materials, and the like. Another object is the preparation of materials suitable for shower-proof suits, dresses, coats, and clothing generally, also for straw hats, umbrellas, shades, curtains, etc. Other objects will appear hereinafter. g

These objects are accomplished by the following invention wherein a cellulosic material is impregnated with an aqueous or other dispersion of an isothiocyanate or isocyanate having-an alii with rapid stirring.

phatic carbon chain containing at leasteightfi carbon atoms, thendried and (subsequently or simultaneously) heated under conditionsfmorel thoroughly detailed below.

, In carrying out the'processof this inventionf' an aliphatic isocyanate or isothiocyanate containing a hydrocarbon radicalof'at-le'ast eight carbon atoms, e. g., dodecyl i athiocyanate, 9,1 0

ature f of 135" 0.1

octadecenyl isothiocyanate, octadecyl isothiocyatageously be employed. In. order to avoid the use of expensive solvents, it is advantageous to use the said compound in the form of an aqueous emulsion employing, for example, ordinary household or laundry soap as the emulsifying agent. The use of a soap emulsion also insures better penetration and quicker impregnation. The fabric may then be squeezed free of excess liquor to avoid too rapid exhaustion of the bath and then allowed to dry and/or immediately subjected to anelevated temperature such as 125 C. for a period of at least several minutes, or until the fabric is found to have been rendered water-repellent to the desired degree. After this baking operation the fabric is washed free of soap and dried. It is then found to be difllcult to wet with water.

The more detailed practice of the invention'is illustrated by the following examples, wherein parts given are by weight unless otherwise-stated. There are of course many forms of the invention other than these specific embodiments.

Emmple I I Two parts of dodecyl isocyanate was added slow- 1y to'a solution of 3 parts soap in parts water with rapid stirring. A piece of cotton muslin was impregnated with the resulting emulsion,

squeezed free'of excess liquor, thenheated for 1 hours at C. After rinsing and drying,

Example 11 Two parts of octadecylisocyanate wasslowly added to one part of soap and '37 parts of water In. the emulsion thus formed cotton muslin fabric was immersed, then freed of excess liquor and subjected to a temperfor 30 minutes}; After rinsing the fabric was not again easily wet,

the water-repellency impaired after I I I ,%1-soap solut ion 1 followedby rinsing with water. l

and drying, ted, nor was laundering for, V2 hour -tln Example I I t F P8 13 odecyl isothiocyanatewas added l l 's l i orpans Castile soap in 70. pa I'Water, the, solution-beingstirredrap y m h ut the addition. j In the resulting emu;

.fibers were thendried and found to bevery water-repellent which effect was not appreciably impaired by subjection to two one-half hour washings in boiling /z% soap solution. The appearance of the fabric was unchanged while the feel was somewhat softer. The fibers floated on water indefinitely without wetting while the fabric was capable of supporting drops of water until they evaporated. The treated cotton had an increased afilnity for acid dyestuffs normally used on animal fibers while the aflinity for most direct dyes was unchanged.

Example IV Ten parts octadecyl isthiocyanate was melted with two parts of stearic acid and poured very slowly and with rapid stirring into a solution consisting of 4 parts of 10% caustic potash solution, two parts 10% soda solution and 182 parts of water. The emulsion was then run through a colloid mill and was found to be a stable gel when cooled. Cotton muslin was impregnated for 30 seconds in this emulsion at 28 C., squeezed free of excess liquor and heated for 15 minutes at 140 C. It was then rinsed with water and ironed dry.

The fabric was then very water-repellent, evenafter boiling for V. hour in soap solution.

Example V Three parts of cotton muslin was impregnated in an emulsion prepared by adding 0.3 parts of octadecyl isothiocyanate to 0.5 parts soap and 30 parts water with rapid stirring. The fabric was then wrung to a weight of 6 parts and subjected to a temperature of 105 C. for 5 minutes. After rinsing the fabric with water and again drying, it was found to be very water-repellent which effect was resistant to the action of acetone.

Example VI Tenparts 9,10-octadecenyl isothiocyanate was added slowly to a solution of 5 parts castile soap in 70 parts water, the solution being stirred rapidly throughout the addition. In the resulting emulsion 3.5 parts cotton muslin and 6 parts loose cotton fibers were immersed until thoroughly wet. The fabric and fibers were then squeezed free of excess liquor after which they weighed 6.7 parts and 10.4 parts respectively.

After allowing to dry they were then subjected to a temperature of 130 C. for 4 hours. Following this baking treatment the cotton was washed with water and finally acetone to remove the soap and excess unreacted material. Both the fabric and fibers were then dried and found to be very water-repellent which effect was not appreciably impaired by subjection to two one-half hour washings in boiling /2% soap solution. The appearance of the fabric was unchanged while the feel was somewhat softer. The fibers floated on water indefinitely without wetting while the fabric was capable of supporting drops of water until they evaporated. The treated cotton had an increased affinity for acid dyestuffs normally used on animal fibers while the aflinity for most direct dyes was unchanged.

Example VII Ten parts 9,10-octadecenyl isothiocyanate was inelted with two parts stearic acid and poured very slowly and with rapid stirring into a solution consisting of 4 parts of 10% caustic potash solution, two parts 10% soda solution and 182 parts of water. 'The emulsion was then run through a colloid mill and was found to be a stable gel when cooled. Cotton muslin was impregnated for 30 seconds in this emulsion at 28 C., squeezed free of excess liquor and heated for 15 minutes at 140 C. It was then rinsed with water and ironed dry. The fabric was then very waterrepellent, even after boiling for /2 hour in /r soap solution.

Example VIII Three parts of cotton muslin was impregnated in an emulsion prepared by adding 0.3 parts of 9,10-octadecenyl isothiocyanate to 0.5 parts soap and 30 parts water with rapid stirring. The fabric was then wrung to a weight of 6 parts and subjected to a temperature of C. for 5 minutes. After rinsing the fabric with water and again drying, it was found to be very waterrepellent which effect was resistant to the action of acetone.

' Example IX Ten parts octyl isothiocyanate was added slowly to fifty parts of a 5% aqueous solution of soap with rapid stirring. A piece of cotton muslin weighing 5.6 parts was impregnated with this emulsion and squeezed free of excess liquor to a weight of 11.0 parts. The fabric was then dried overnight at 100 C., then washed with water and ironed. It was then "spot-proof, being capable of shedding drops of water placed thereupon momentarily.

Example X Five parts decamethylene diisothiocyanate was emulsified in 15 parts of a 3% aqueous soap solution. Five parts cotton voile fabric was thoroughly wet out in this emulsion and wrung to a weight of 9 parts. Half of this fabric was dried over night at 95-100 C. and the other half 45 minutes at C. Each half was then rinsed with water and dried. Both pieces of voile, al-

though of open weave, were very water-repellent and supported drops of water without wetting even after repeated washing with actone or soap.

Example XI After rinsing out the soap the fabric was defi-,

nitely water-repellent.

There may be employed in the process of this invention any water-insoluble aliphatic compound containing at least 8. and preferably from 12-18, carbon atoms and one or more isocyanate or isothiocyanate radicals attached by the nitrogen atom to one or more carbon atoms, respectively, of the hydrocarbon chain. While the examples disclose isocyanates and isothiocyanates of alcohols of eight to eighteen carbon atoms in the alkyl group, isocyanates and isothiocyanates wherein the hydrocarbon is of higher carbon content may be employed, e. g. melissyl. The isocyanates and isothiocyanate's of alcohols o1. twelve to eighteen carbon atoms are greatly prehydrocarbon radical of at least eight carbon atoms having a valence oi y, 'x is oxygen or sulfur and 11 is an integer which is at least one, are

, particularly useful and are of generic utility.

In addition to the isocyanates and isothiocyanates'of the examples there may be employed such compounds as the isocyanic or isothiocyanic esters of linolyl-, 1inoley1-, eleostearyl-, melissyl-, and 1,2-chloro-octadecyl alcohol, or the isocyanate or isothiocyanate of such glycerol esteralcohols as castor oil or hexahydro-castor oil (glyceryl tris-hydroxystearate) Any fabric, yamor fiber may be used so long as it is cellulosic, as for example, cotton, linen, Jute, ramie, viscose silk, etc. The term cellulosic" is used to include cellulose but not cellulose ethers or esters.

The process of the present invention is most effective in causing fibrous cellulosic materials to attain water repellency and this forms a preferred class of cellulosic materials. In the case of non-fibrous cellulosic materials, e. 8., those sold under the registered trade-mark Cellophane, the process while effective to some extent is not commercially feasible.

The reagents may be applied to the cellulosic required'degree.

When a cellulosic material, e. g., a fabric, is made water-repellent according tothe methods already known, namely by impregnation with an emulsion or solution of a material such as a high molecular weight ester or a waxy hydrocarbon or other material which is deposited in or on the fibers, thereby imparting to said fibers the inherent water-repellent properties of the agent used, permanent laundry fastness is not obtained. Adhering mechanically to the fibers, this material is'of course removed by laundering with soap or material in any manner desired though preferably in the form of an aqueous emulsion using any neutral soap, such as castile" alkaline soap, himolal salts, etc. in sufflcient quantity to disperse the oil in the aqueous phase. The reagent may be employed in any concentration in excess of about 1%, or even less, of the total'solution or emulsion while the preferred con-' centration ranges from about 1% to about 25%. Theratio of the amount of reagent to the cleaning with organic solvents. We do not wish to'be limited by any theory but it appears that when a fabric is treated in accordance with this invention with a long chainvalkyl 'isocyanate or isothiocyanate, the cellulose on the surface of the fibers reacts to form a urethane or thio-urethane in the following manner, where Cell-0H stands for a portionof the cellulose molecule:

" Ce11OH+C1aH3jlNCS-' Ce1lO-CSNHC1aH31 Since the cellulose thus becomes chemically 'attached to the water-repellent agent, the effect is not lost by mechanical treatment with soaps or organic solvents. The invention is not however limited to this theory. The water-repellency of the treated fabric is not adequate unless the R of R-N=C=X contains at least eight carbon atoms and is more satisfactory when R contains at least twelve carbon atoms.

The products of this invention are particularly useful in any applicationwhere a water-repellent vfabric is desired and where the fabric must occasionally be laundered or dry cleaned as for example inthe case of shower-proof dresses, suits and coatsrin fact cotton-or cellulose-containing I clothing in general, also spot-proof table cloths,

amount of textile material is immaterial as long' i as suilicient liquid is present to cause uniform wetting. The time necessary for immersion is in no way limited, exceptthat the goods mustbe v uniformly impregnated. They1may or may not be freed of excess liquor "and may or-may "not be dried at room temperature before baking, as

desired. The temperature of the baking treatmentmay be varied from about-80 C.-to.about 160 C., (i. e., fromthe temperatureat whichthe reaction rate begins to "be appreciable, up; to the temperature at which chairing-begins) theftime required withgiven materials being in inverse proportion to the temperature. 'At' andv below doilies, etc. Even papergmay be given water repellent properties by this treatment. It has been'pointed out abovethat the process herein described for the production'of water-repellent textile materialsis superior to methods'involvin'g filling of the interstices "of the'fabric or surface-coating the fiber in thatthefgoods are left substantially unchanged in appearance and feel. It isalso superior tomethods involving simple mechanical impregnation with waterrepellent agents in tha-tthewater-repellent effect is not readily removed by laundering.

The *above descriptionand'examples are in-' tended to-be: illustrative only. modification of or --var iation therefrom which conforms to the approximately 100 C.,- the reaction'rate is so slow that several hoursgmay be requiredto' obtain the desiredflresult, .whilethe desiredeifect may be obtained his few: minutes when using a temperature' approaching that .at whichscorching' spirit of the invention is-jintended to be included within the scope. 'of the claims,

weclaimz r 1. Process which comprises baking at a temperature of 80 160? C. aicellulosic fabric impregof thefabric occurs (1.. e. approximately 160 0.). In general no harm results from continuing the baking; beyond the point where the reaction is I completed, providingit" isnot' continued until I charring orscorchingisappreciable.

" The baking steplis not a mere drying since drylngi at' room. temperature doesknot produce water-repellent effects. .Areactioneither with the celluloseor intramolecularlyliscaused itthe r The temperatures andjtimesg'iven'in theexnated-with anisothiocyanic acid ester of an allphatic alcohol of at least eight carbon atoms, until the fabric becomes water-repellent.

2. Process which comprises baking at a temperature of -160 C. a cellulosic fabric impregnated with an alkyl isothiocyanate, the 'alkyl group of which contains at least eight carbon atoms untilthe fabric becomes water-repellent.

amples gre not'intendedtobathe neces:

.ja y'. Tenineratursbetween80 and 16o cans ii e e a ri-b tween ;a d 1 ar selected wh r ver, tantr ms-1m rgari a-"i 'grpziup of 'which contains j12'to 18 3.: Process which comprises, baking .at a temvperature bf 80- C. a cellulosic fabric impreg- 70' nated with an alkyl' isothiocyanate, the alkyl 7 carbon atoms, until the fabric becomeswater-repellent.

4.1 Process which comprises-baking a cellulosic fabric, impregnated with octadecyl isothiocyanate, at a temperature between about'80. and

160 until the fabric becomes water-repellent.

5. Process which comprises impregnating a celimpregnated with an isothiocyanic acid ester of an aliphatic alcohol of at least eight carbon atoms, until the fabric becomes water-repellent.

9. A process which comprises impregnating a, cellulose textile material with an isothiocyanate of the formula RNCS in which R is an aliphatic hydrocarbon radical containing more than seven carbon atoms, and heating the impregnated material until the material becomes water-repellent.

10. A process which comprises impregnating a cllulose textile material with octadeeyl isothioass-gees cyanate and heating the impregnated material until the material becomes water-repellent.

11. A process which comprises impregnating a cellulose textile material with an isothiocyanate of the formula RNCS in which R is an aliphatic hydrocarbon radical containing more than ten carbon atoms, and heating the impregnated material until thematerial becomes water-repellent.

12. Water-repellent material comprising a cellulosic material impregnated with 9,10-octadecenyl isothiocyanate and baked at a temperature of 80 to 160 C. until the fabric becomes water repellent.

13. Water-repellent material comprising a cellulosic material impregnated with dodecyl isothiocyanate and bakedat a temperature of 80 to 160 C. until the fabric becomes water repellent.

14. Process which comprises baking at a temperature of 80 to 160 C. a1 cellulosic fabric impregnated with 9,10-octadecenyl isothiocyanate until the fabric becomes water repellent.

15. Process which comprises baking at a temperature of 80 to 160 C. a cellulosic fabric impregnated with dodecyl isothiocyanate until the fabric becomes water repellent.

WILLIAM E. HANFORD. DONALD F. HOLMES. 

